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The weakest link

18 August 2001

By Arran Frood in London

SAVING the world used to be the job of superheroes. But now, with millions of
plant and animal species facing extinction, it’s down to us mere mortals. Where
do we begin? We don’t even know how many species are out there. And even if we
did, the numbers are meaningless until we know how the different species
interact.

Collecting all this detail is a Herculean task. Yet without the detail, how
can we know which human activities are most likely to have apocalyptic
consequences, let alone work out ways to avoid them?

What we need is a way to make predictions based on the information we already
have. But the fledgling science of ecology has struggled to describe the natural
world, let alone understand it. Like early astronomers, ecologists are faced
with a unique system that doesn’t lend itself to scientific methods such as
experimentation, replication or manipulation. However, just as stargazers learnt
to predict eclipses and alignments of planets, ecologists are now starting to
build models that can explain patterns in nature and help predict how ecosystems
will react to change.

One pioneer of this approach to understanding biocomplexity is Neo Martinez
from San Francisco State University in California. He has made a career of
studying food webs—in other words, who eats who within any ecosystem.
Charles Darwin once described such webs as intractable “tangled banks”. But
Martinez is starting to trace the strands that tie the beautiful mess together.
He has come up with a way to discover how the animals and plants in a given
community interact, without resorting to exhaustive …